Zac Efron angered many fans with a tweet on Monday, which happened to be Martin Luther King Day.

The Dirty Grandpa actor was slammed on Twitter after he wrote, “I’m grateful for a couple things today: Martin Luther King Jr & 10 million followers on IG,” along with a raised fist emoji and pointing index emoji, both in black skin tone.

The following day, Efron, 28, deleted the post and issued an apology to his 21 million social media followers. “I have nothing but the greatest admiration and respect for Dr. Martin Luther King Jr. I realize that last night’s post was completely insensitive and I apologize to anyone who I may have offended. So sorry,” he shared on Instagram.